JPS6234626A - Manufacture of electric welded pipe - Google Patents

Abstract

PURPOSE:To use an equipment in common for electric welded pipes whose diameter is different from each other, by curving only a side edge part of a metallic plate, centering around an axis running along its longitudinal direction, and subsequently, bending the center part of the metallic plate in the same direction as the side edge part. CONSTITUTION:In a breakdown pre-stage being the first forming process, bending is performed to both side edge parts 11a, 11b of a metallic plate 10 such as band steel, etc. Its working shape is a curved shape centering around an axis running along the longitudinal direction of the metallic plate 10, and its radius is matched to a radius of a caliber in a fin pass roll which is executed thereafter. Subsequently, in the second forming process of a breakdown post- stage, bending forming is performed to the center part of the metallic plate 10 in the same direction as the side edge parts 11a, 11b. Next, forming by the fin pass roll is executed, the side edge parts 11a, 11b are made symmetrical, and unworked parts 16a, 16b are left as they are. The side edge parts 11a, 11b which have been formed in this way are detained by a squeeze roll, butted and welded. A cylindrical body which has been obtained in the end is formed to a true circle having an object outside diameter by a sizing process.

Description

Detailed Description of the Invention 3. Brief Description of the Invention Industrial Application Field The present invention relates to a method for manufacturing electric wires, especially wires of different diameters. The present invention relates to a manufacturing method that allows equipment to be used for sewing pipes.

As is well known in the art, electric steel pipes are produced by forming a steel strip sent from a coil into a cylindrical open pipe in a forming process, welding the side edges of the butted steel strips, and then sizing this. It is manufactured by giving it a slight squeeze during the process and finishing it into the desired size and shape. In the forming process of these manufacturing processes, the conventional method is to gradually form the steel strip into a cylindrical shape using breakdown rolls or side rolls that are shaped like a drum.
Alternatively, the steel strip is formed into a cylindrical shape using a number of cage rolls whose axes have different inclination angles, and then the side edges of the steel strip are adjusted using fin pass rolls to form the strip roughly into a cylindrical shape. While the steel is restrained with squeeze rolls, the butted side edges are welded.
1 However, in the past, such a forming process
In order to do this, the entire strip in the width direction is gradually bent so that the curvature at each part in the width direction gradually approaches the curvature of the steel pipe with the radius to be finally obtained. Use rolls whose outer peripheral surface has a curvature corresponding to the radius of curvature of the steel pipe to be obtained, or in the case of a full cage forming mill, rolls arranged in accordance with the curvature of the steel pipe to the radius to obtain the Gale rolls. There is. Therefore, when changing the outer diameter of the steel pipe to be manufactured, all the rolls must be changed to rolls with a new curvature.For this reason, the method described above requires a large number of rolls, and Including exchange! ! There were problems such as it took a long time to change Qa and the operating sf+ decreased.

In order to eliminate such inconveniences, a method that allows rolls to be used for making pipes of different diameters was proposed, for example, in the Japanese Patent Publication No. 5
This is proposed by Japanese Patent No. 7-1328. This method is shown schematically in FIG. 41 is fed into the vertical roll group 3 by the push roll 2, where the steel strip 1 is bent, and then passed through the fin roll group 4 to form a cylindrical shape. As shown in FIG. 7, the vertical rolls 5 are configured to have four corner parts 7 that engage the side edges of the steel strip 1. By applying pressure to the band 811 from the left and right sides, the steel band 1 is bent. Therefore, by changing the spacing and the width of the vertical rolls 5, it can be applied to various board widths, so the same vertical roll can be used to produce mw of various radii! ! can be built.

Problems to be Solved by the Invention However, in the method according to Japanese Patent Publication No. 57-1328 mentioned above, when the steel strip is pressed in the width direction by the pair of vertical rolls on the right side, almost the entire width of the steel strip is pressed. Even though bending occurs in the steel strip, the steel strip is only restrained by its side edges, so the restraining force of the steel strip is insufficient, making the steel strip unstable during forming, and causing the strip to become unstable. Rolling of the steel may not be properly dealt with, or if rolling occurs, forming defects may occur. The method described above is essentially a method of holding the steel strip in a free state and performing bending while balancing the bending force applied in the width direction by vertical rolls and the deformation resistance of the steel strip. There are many factors that disrupt the mechanical balance that causes bending, and for example, the position of the vertical rolls greatly affects bending, making it extremely difficult to set their positions accurately. Furthermore, in the method described above, roles can be used only in breakdown,
It is not possible to use the fin pass roll for multiple purposes.

As described above, the method according to the above proposal has a narrow scope in which the rolls can be used interchangeably, and there are various difficulties in implementing it as described above, making it difficult to put it into practical use.

In view of the above-mentioned circumstances, it is an object of the present invention to provide an easy-to-implement method of manufacturing electric conduit tubes that expands the range of dual use of rolls.

Means for Solving the Problems The present invention achieves the above object by carrying out construction through the following steps. That is, in this invention, only the side edges of a metal plate as a material are bent, curved in a certain direction about an axis along the longitudinal direction, and then the center part of the metal plate is bent in the same direction as the side edges. Perform the bending process.

In this case, the center portion is curved to the minimum radius of curvature that can be produced with the equipment used, and therefore, if the plate width is large, an unprocessed portion is left between the edges that have already been bent. Since both side edges approach each other by bending the central portion, the side edges are formed by fin pass rolls and butted to a weldable state. Here, in the case of a pipe with the minimum outer diameter that can be produced with the equipment used, it is formed into a circular cross section using fin pass rolls, and in the case of a pipe with a larger diameter, it is formed into an oval cross section. Can you do molding like this? After that, the butted side edges are welded while being restrained from both sides with squeeze rolls.

Then, the obtained cylindrical body is finished into a predetermined size and shape in the next sizing process.

Function: Among the steps in the manufacturing method of the present invention, the first bending step involves bending only the edges on both sides, so, for example, the upper and lower horizontal rolls are divided into two in the axial direction, and the divided rolls are It is only necessary to adjust the interval in the axial direction to match the width of the plate, and therefore, this additional bending process becomes a processing process in which rolls can be used in combination when pipes with different diameters are made.

Further, in the bending process of the center part, since an unprocessed part may be left between the center part and the side edge parts, there is no particular restriction on the board width, and therefore, rolls can also be used for this process. Furthermore, forming with fin-pass rolls involves bending the central part and abutting the side edges that are close together in a weldable state, and does not specifically form into a circular cross section, so the rolls used are , ti It is not necessary to have an outer circumferential surface that matches the curvature of the pipe to be produced, and therefore, in this process as well, the fin pass roll can be used for producing pipes of various diameters. The shape of the cylindrical body obtained in the above steps has an oval cross section except for the tube with the minimum outer diameter that can be manufactured, but this is finished into the desired circular cross section in the sizing process after welding.

Actual example Hereinafter, this invention will be specifically explained based on examples.

Figures 1 (A) to (E) show flower shapes (cross-sectional shapes of materials) from the pre-breakdown stage to sizing for small diameter pipes and large diameter pipes, and Figures 2 (A) to (
D) is a diagram showing the roll shape for forming the flower shape shown in the first factors (A) to (D). Bending is performed on both side edges 11a and 11b. The processed shape here is a curved shape centered on the axis along the longitudinal direction of the metal plate 10, and its radius R matches the radius of the caliber in the fin pass roll performed later.

Further, in this case, since the processing area is naturally only the side edge portion of the entire width of the metal plate 10, the rolls for this purpose include the upper roll 12 and the lower roll 13 with their axes aligned as shown in FIG. 2(A). It is divided into two parts at the center of the direction,
In the case of manufacturing a small diameter pipe as shown in the left half of Fig. 1 (A), move the v1 portion of each upper and lower roll of 12°13 to the center C side as shown in the left half of Fig. 2 (A), and Figure 1 (A
) In the case of manufacturing large diameter pipes shown in the right half of Figure 2 (A)
As shown in the right half of the figure, the divided parts of the upper and lower rolls 12 and 13 are separated from each other and set to match the width of the board.

To show this more specifically, as shown in Fig. 3, the Itil (axial length) W of each upper and lower roll 12. The total width when the .13 divided parts are separated is
A spacer 14 whose dimensions correspond to a preset outer diameter ratio to the applicable minimum outer diameter is provided, and in the case of manufacturing small diameter pipes, the spacer 14 is moved in the axial direction as shown in the left half of Fig. 3. In the case of manufacturing large diameter pipes, a spacer 14 is placed in the center of each roll 12.
The interval between the divided parts at 13 is widened.

The second stage after the break run following the first forming process described above.
In the forming process, as shown in FIG. 1(B) and FIG. 2(B), the side edge portions 11a, 11
This is done by bending in the same direction as b. The bending radius in this case is a dimension that takes into account the radius of the small diameter pipe to be manufactured. Therefore, regardless of whether it is a small diameter pipe or a large diameter pipe, the bending process has already been applied to the central bent part 15. An unprocessed portion 16a is formed between the side edges 11a and 11b.
, 16b will remain. Also, naturally, the upper and lower rolls 17, 18 for performing such forming may be of one type as shown in FIG. 2 (8).

Following the breakdown in the first and second molding steps described above, molding using fin pass rolls is performed. The forming here is to punish the subsequent welding, so the side edge 1
1a and 11b, and the aforementioned unprocessed parts 16a and 16b are left as they are. That is, forming is performed using upper and lower rolls so that the edge of the metal plate 10 butts against the fins of the fin pass roll. In this case, if the pipe is a small diameter pipe, the unprocessed portion 16 is formed as shown in the left half of FIG. 1(C).
a and 16b remain short, and if it is a large diameter pipe, see Figure 1 (C
), large unprocessed portions 16a and 16b remain as shown in the right half. Such processing is performed by setting the distance between the fin pass roll 19 and the lower roll 20 according to the diameter of the tube to be manufactured, that is, the width of the metal plate 10, as shown in FIG. 2(C). Therefore, the rolls can be used for both small diameter pipes and large diameter pipes. In addition, in the case of large diameter pipes, the distance between the upper and lower O-ru 19.20 may become too wide, in which case the fourth
As shown in the figure, it is preferable to provide a pair of side rolls 21 and 22 to prevent bulging.

The side n portions 11a and 11b formed in the above manner are
! In the subsequent fourth forming process, they are butted together and welded while being restrained by squeeze rolls. In the case of a pipe with the minimum outer diameter applicable here, the left half of Fig. 1 (D) is formed simultaneously into a perfect circle as shown; in other cases, the right half of Fig. 1 (D) is shown. It is welded as an oblong tube. Such processing may be performed using a pair of squeeze rolls 23 and 24 of a caliber depending on the tube shape to be obtained, as shown in the left half or right half of FIG. 2(D).

Finally, the cylindrical body that has been cut into 1q as described above is given a slight reduction in the sizing process while being
It is formed into a perfect circle with the desired outer diameter as shown in Figure (E). In the case of a small-diameter tube with the minimum external diameter applicable here, since it has been formed into a perfectly round tube in the steps up to this point, the sizing process will be performed using a perfectly round caliber sizing roll, as has been conventionally done. However, in the case of other tubes, they are welded as oval tubes, so
First, an ellipse is formed into a perfect circle, and the outer diameter and roundness are adjusted according to Wkn. An example of this is shown in Fig. 5 (A> shows the process of changing the cross-sectional shape, and Fig. 1i1 (B) shows the caliber shape. In the example shown here, the number of stands is 4 and the squeeze process SQ is A cylindrical body with an oval cross section is formed into a perfect circle by the first to third stands 5l=Ss, and in the fourth stand S4, the outer diameter and roundness are adjusted using a roll of a conventional perfect circle caliber. Make adjustments.In addition, it is preferable that the overbend portions above and below the snow be bent back almost equally in each stand from Ml to the third stand.

However, in the above-mentioned process, from the pre-breakdown stage to the fin bath, processing is done only partially and does not cover the entire metal plate, so there are restrictions on the outer diameter of the tube to be obtained, that is, the width of the metal plate. It is possible to use rolls that do not have the same purpose, and the rolls can be used for multiple purposes.

Effects of the Invention As is clear from the above explanation, according to the method of the present invention, except for the pipe with the minimum applicable outer diameter, processing is limited to the 81 edge or center of the metal plate in the process up to the fin bath process, Since it is formed into a cylindrical body, not only the breakdown roll but also the fin pass roll can be made without being restricted by the width of the metal plate, that is, the outer diameter of the tube to be obtained. According to LIT! It is possible to reduce the time required for O-role changes, reduce the number of roll changes, and further reduce the number and types of rolls that must be kept, thereby reducing maintenance costs. Moreover, by adjusting the roll interval, it is also possible to produce a product with a middle gate size. Further, the forming in the method of the present invention can be carried out by feeding a metal plate between an upper roll and a lower roll, and there is no particular difficulty in setting the position of the rolls, so it can be easily carried out.

[Brief explanation of the drawing]

FIGS. 1(A) to (E) are diagrams showing flower shapes according to the present invention in order for small diameter pipes and large diameter pipes, and FIGS. 2(A) to (E)
D) is a cross-sectional view showing roll shapes that can be used up to the squeeze step in the method of this invention for forming small diameter pipes and large diameter pipes, and Figure 3 is a cross-sectional view showing roll shapes that can be used up to the squeeze step in the method of this invention. FIG. 4 is a partial explanatory diagram showing an example of a roll width setting method. FIG.
A) is an end view showing the change in cross-sectional shape in the sizing process, FIG. 5(B) is an explanatory diagram showing the caliber shape of the roll used in the sizing process, and FIG.
FIG. 7 is a schematic diagram illustrating the molding method in the plackdown process. 10...Metal plate, 11a, 1 lb/l!
! Edge, 15...Central bent part, 16a, 1
6b...unprocessed portion, 19...fin pass roll, 23,24...squeeze roll.

Claims (1)

[Claims] In addition to bending a metal plate and forming it into a tube shape,
When making a pipe by welding the side edges of butted metal plates, only the side edges of the metal plates are curved in a certain direction around the longitudinal axis, and then the gap between the side edges and The central part of the metal plate is curved in the same direction as the side edges, leaving an unprocessed part, and then the curved side edges are butted together in a weldable state with a fin pass roll, and further with a squeeze roll. Weld the butted side edges while restraining,
A method for manufacturing an electric resistance welded pipe, which is characterized in that the pipe is then finished into a predetermined size and shape in a sizing process.